Reported today in The journal Science U.S. Geological Survey seismologist Susan Hough and USGS geophysicist Morgan Page in Pasadena, Calif.,latest study suggests, past quakes in the New Madrid region are not signs of a dead zone but something more, and used computer modeling to determine that the continuing tremors are not related to the big quakes two centuries ago.

"Our new results tell us that something is going on there, and therefore a repeat of the 1811-1812 sequence is possible," Hough said.

The USGS estimates there's a 7 to 10 percent chance of that happening in the next 50 years.